In short: this is due to the way we are “wired” as species, so this is perceived a hard limit in a sense. The trustees are falling, by the nature of the stuff they do and how they communicate, into the “small group” region, and the magical numbers for that are 6-8, max 9. (That is maximum efficiency at ~7 and you cannot go over 9 (of actively participating people) realistically).

So, it’s pretty easy to do the math here. 350 > 9. Conclusion being that the large-scale gentoo-dev list is not the best way to develop — rather, smaller lists and projects are. But then, how does one accomplish anything project-spanning? Presumably by resorting to a republic, as Michael Cummings said, the decision could be made by a small enough group of people representative of Gentoo as a whole.